The present invention relates to syringes, and more particularly to vial syringes capable of limiting the dosage dispensed to a predetermined amount.
The medical community is constantly striving to reduce errors wherever possible. One area of particular concern is controlling the amount of dosage administered to medical patients, particularly in emergency or high stress situations. Some studies have shown that incorrect dosages of emergency resuscitation drugs are mistakenly given in an emergency setting more than 40% of the time.
Some medical errors occur because of dosage miscalculation or dosage administration. Known medication packaging requires multiple calculations be made in order to deliver an appropriate dose. While these conversions are not necessarily complicated, they can be tedious and/or difficult to calculate in high pressure environments, such as an emergency department. An error in dosage calculation can have devastating consequences.
Some syringes are designed to reduce dosage miscalculation by labeling the syringe barrel with non-volumetric measuring indicia to eliminate weight to dosage conversions. An example of one such construction is shown in U.S. patent application Ser. No. 10/074,009 to Slishman. This construction only helps to reduce dosage miscalculation and does nothing to help reduce dosage administration errors. That is, the syringe operator is still burdened with the requirement of watching the graduations on the container as an appropriate amount of medication is drawn into the syringes. In some syringes, the container is funnel shaped, meaning the rate of withdrawal of the medication will change as more volume is withdrawn, increasing the time to withdraw appropriate amount of medication and risking and overshoot and withdrawing too much.
Other syringes are aimed specifically to reduce errors in dosage administration. Examples of such syringes includes U.S. Pat. No. 4,444,335 to Wood, U.S. Pat. No. 4,874,385 to Moran, and U.S. Pat. No. 4,654,035 to Ando. Each of these constructions use a mechanical stopping element attached to the syringe plunger to physically limit syringe plunger movement and thereby control dosage.
Each of the syringes discussed above requires the user to draw medication into the syringe before it can be dispensed. In some syringes, pre-filled vials replace the syringe plunger and obviate the need to draw medication into the syringe. This can be especially valuable in time sensitive situations such as an emergency department. The vial syringe works by inserting a vial into an injector and rotating the vial clockwise a specific number of turns, medication enters the injector needle, whereupon the injector is uncapped and ready for use. An example of one such construction is the Abboject syringe manufactured by Abbott Laboratories. Some vial syringes use vials that contain one adult dosage, so there is little possibility of dosage miscalculation or dosage administration error. Unfortunately, sometimes a one size fits all dosage is not appropriate. Specifically, some resuscitation drugs are packaged for adults which results in potential error when a smaller dose must be delivered to a child. That is, at times, less than or more than a single adult dose may have to be administered.
Some vial syringes use vials which contain multiple dosages and rely on the user to judge the amount injected using graduations on the syringe barrel. Although the user saves time not having to draw the medication, multi-dose vial syringes still require the user to watch graduations on the barrel so as not to under or overdose. Unfortunately, a vial syringe does not have a plunger, hence the mechanical stopping elements described in the patents above are unhelpful.
Previous devices fail to meet the needs of the medical community for error reduction. In the high pressure situation of a patient in cardiac arrest or near death, especially a pediatric patient, it is too easy to administer an incorrect dosage using known syringe constructions.